Method for operating heating systems, heating system for carrying out the method and use thereof

ABSTRACT

A method for operating solar and/or solar-operated and/or heat absorbing and/or heat accumulating heating systems includes exchanging at least one fluid for at least one operating function such as a protective function or heat function and/or maintaining the fluid in a standby position. This enables a direct heat exchange to occur between media such as fluids, gas and fluid, emulsion and fluid, whereby the standby state can occur without any exchange of fluid. This enables the heating system to be protected e.g. from frost or from boiling, and enables heat functions such as storage, production and heating to be performed in a more economic manner involving a reduced number of components. Solar collectors with various height loops can also be operated directly in a heating system.

CROSS-REFERENCE TO RELATED APPLICATION

This is a continuing application, under 35 U.S.C. § 120, of copendinginternational application No. PCT/EP2003/013236, filed Nov. 25, 2003,which designated the United States; this application also claims thepriority, under 35 U.S.C. § 119, of German patent application No. 102 57309.3, filed Nov. 30, 2002; the prior applications are herewithincorporated by reference in their entirety.

BACKGROUND OF THE INVENTION Field of the Invention

The invention relates to a method for operating solar and/orsubstance-operated and/or heat-absorbing and/or heat-storing heatingsystems.

The general state of the art discloses solar circulating systems thatuse a water-glycol mixture for frost protection in heating systems.However, this requires that heat exchangers have to be used for thesolar circulation, causing the disadvantage of heat exchanger losses,pressure losses and higher operating costs due to a greater circulatingvolume.

In the case of these solar systems, the water-glycol mixture isdisplaced from the solar collector at boiling temperature, whereby thesolar system can no longer be operated under further solar radiation,but only after the solar collector has cooled down.

Furthermore, there are known heat-exchanging systems that are emptiedand filled with inert gas for frost protection, whereby theaforementioned disadvantages can be avoided, but for which fillingdevices are required. These also have to be elaborately controlled,partly to avoid the mixing of different temperatures or for venting.

SUMMARY OF THE INVENTION

It is accordingly an object of the invention to provide a method foroperating heating systems, heating system for carrying out the methodand use thereof which overcomes the above-mentioned disadvantages of theprior art methods and devices of this general type, which ensures frostprotection in a simple and safe manner while avoiding the disadvantagesof the known heating systems, so that a heating system which manageswithout, or with reduced, heat exchangers or absorbers between heatsources and storage reservoirs and heat emitting elements can beconfigured. This is intended to increase the cost-effectiveness forlinking up further heat exchange systems with protective functions andthermal functions, so that regenerative energy sources can be betterused.

In addition, further operating functions of a heating system are to besupported, whereby functional additions and improvements and also costoptimizations are to be obtained, in particular in connection withregenerative energy production and storage. In particular, the linkingup of solar heat generators with any height loops is to be madepossible, the heat exchange with the heating system managing withoutheat exchangers.

According to the invention, the object is achieved by at least one fluidfor at least one operating function, such as a protective function orthermal function, being exchanged and/or kept on standby for operatingsolar and/or substance-operated and/or heat-absorbing and/orheat-storing heating systems, it being possible for a direct heatexchange to take place between media, such as fluids, gas and fluid oremulsion and fluid, and taking place without fluid exchange in thestandby state.

During the operation of the heating system, the protective functions:frost protection, boiling protection, excessive temperature protection,corrosion protection, are achieved by the aforementioned methodaccording to the invention. Furthermore, thermal functions, such as heatexchange or transfer, heat storage, heat absorption, heat emission,solar absorption, heat collection, heat distribution, heat utilization,charging, provision on standby, can be better used or extended.

The invention also relates to a device for heating systems that isanalogously based on the same object as the method. This object isachieved by the features of a heating system having at least one of thefollowing devices: a fluid exchange device, a fluid standby device, adevice for direct heat exchange between media, a device for introducingand/or discharging media, a separating device, such as areverse-emulsification device or an emulsion avoiding device.

The invention also relates to use of devices and/or methods foroperating heating systems in the form that such devices and/or methodsare used for controlled ventilation and/or for regenerative use of heat.In the controlled ventilation, for example, the supply air may be passedthrough the storage heat exchanger for heat exchanging purposes and theheat recycled from the exhaust air. In comparison with the prior art ofheat recovery with air-air heat exchangers, the methods and devices havethe advantage that the air can be simultaneously filtered through water,and the storage heat exchanger can be used for storing heat for examplefrom the air.

Other features which are considered as characteristic for the inventionare set forth in the appended claims.

Although the invention is illustrated and described herein as embodiedin a method for operating heating systems, heating system for carryingout the method and use thereof, it is nevertheless not intended to belimited to the details shown, since various modifications and structuralchanges may be made therein without departing from the spirit of theinvention and within the scope and range of equivalents of the claims.

The construction and method of operation of the invention, however,together with additional objects and advantages thereof will be bestunderstood from the following description of specific embodiments whenread in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagrammatic, illustration of a fluid exchange device on asolar heating system;

FIG. 2 is an illustration of the fluid exchange device with a chargingand provision-on-standby device and fluid heat exchange;

FIG. 3 is an illustration of the fluid exchange device with ahigh-temperature storage reservoir; and

FIG. 4 is an illustration of a system with fluid standby and heatexchange conduction.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to the figures of the drawing in detail and first,particularly, to FIG. 1 thereof, there is shown a form of a method foroperating a heating system according to the defined object of theinvention. In this case, a layer of oil 3 is provided in a storagereservoir 7 and an inert gas tank 1, floating on the water of thestorage reservoir 7. A return 2 of a solar collector circulating systemopens out in the layer of oil 3. For frost protection, an exchangeshut-off valve 12 is closed and an exchange valve 11 is opened by acontrol device 13. This allows the water in the solar collectorcirculating system to escape by gravity into the fluid receiving tank10, whereby the oil is drawn from the layer of oil 3 into the solarcollector circulating system.

The control device 13 can detect by a fluid differentiating sensor 8that the oil has safely reached this point, and the control device 13can close the exchange valve 11, so that the frost protection is ensuredby the oil in the part of the circulating system that is at risk fromfrost. However, the limitation of the fluid receiving tank 10, wherebyas much water is emptied and oil filled as fits into the part of theheat exchange system that is at risk from frost, is sufficient forproducing frost protection.

If there is a request for heat exchange with the solar collector fromthe solar control, a circulating pump 9 is started by the control device13 and the exchange valve 11 is opened. As a result, the water containedis pumped into the solar collector circulating system and the oil isreturned into the storage reservoir 7. After a defined time, or by alevel sensor in a fluid receiving tank 10, the exchange valve 11 isclosed and the exchange shut-off valve 12 is opened, so that the normalcirculation through the solar collector can take place.

The triggering of the frost protection can take place by a temperaturesensor 6 in the solar collector, which the control device 13 evaluates.

The fluid exchange device in the case of the system in FIG. 1 may alsobe activated in the operating functions of boiling protection orcorrosion protection. The high boiling temperature of the oil ensuresboiling protection. The fluid exchange also advantageously has theeffect that the solar collector can be operated again at any time, bycontrast with fluid-displacing systems. In the case of unpressurizedheating systems, the penetration of oxygen can be prevented with the aidof the oil, since the oil displaces the air due to the higher pressureand itself does not absorb any oxygen, whereby corrosion protection isensured.

Represented in FIG. 2 by the example of a solar circuit are furtheradvantageous developments, which additionally make it possible for thestorage reservoir to be charged with heat and heat to be provided fromthe storage reservoir at appropriate temperatures, with fluid heatexchange. Since in this example a protective fluid 17 is also operatedby the system as a heat transfer fluid, which is lighter than fluid inthe storage reservoir 36, it is appropriate to operate the heat exchangecircuit from top to bottom, since the lighter heat transfer fluid canthen rise in the storage reservoir. This requires the exchange shut-offvalve 12 and the fluid receiving tank 10 to be fitted upstream of thepump, and also the use of a nonreturn valve 25 on the line to thestorage reservoir. As a difference from the system in FIG. 1, however,the exchange shut-off valve is only closed when the fluid is pumped backfrom the fluid receiving tank 10 into the storage reservoir 36 andopened again for circulating in the heat exchange circuit when theexchange valve 11 is closed. The return of fluid from the storagereservoir 36 is prevented by the nonreturn valve 25.

Fitted in the storage reservoir is a fluid standby device with adistributing function 21 and a positionable fluid standby device with acollecting function 19 and with a flexible line 18 to the flow of a heatcircuit 16. An additional line 14 to the flow of the heat circuit, whichcan be closed by a valve 15, opens out in a standby layer for theprotective fluid 17.

The heat circuit of the solar collector may be operated with a heattransfer fluid for example oil, which is lighter than the storagereservoir fluid for example water, resistant to frost, boiling andcorrosion. The standby devices 21, 19 keep the heat transfer fluidcirculating during the circulation. The standby device with distributingfunction 21 is thereby filled by the pump 9 and emptied over the edge ofthe downwardly open tank, so that there forms a fluid curtain, whichrises upward in the storage reservoir. The thin curtain produces goodheat exchange and heat transfer to the storage reservoir fluid. The heatexchange may also be increased by forming a number of curtains at thelower edge of the standby device with the aid of slits or by formingmany thin flows by use of holes. However, the standby device 21 isconfigured in such a way that it can never be emptied completely by thelighter heat transfer fluid. The fact that the storage reservoir flowopens out in the area of the heat transfer fluid also results in that nostorage reservoir fluid can get into the heat exchange circuit, sincereturn is also prevented by the nonreturn valve 25.

The standby device with the collecting device 19 is configured in such away that it overlaps with the distributing device 19 and in this way theheat transfer fluid is guaranteed to be collected and transferred viathe flexible line 18 back into the flow of the heat exchanger circuit.The collecting device 19 is likewise configured as a downwardly opentank.

However, during the fluid heat exchange in the storage reservoir thereis the problem that emulsions can form as a result of the free flow ofthe fluids in one another, whereby the heat transfer fluid is slowlydisplaced from the heat exchange circuit and storage reservoir waterwould get into the heat exchange circuit, which would impair theprotective functions. This problem is solved by the standby device 19containing sufficient heat transfer fluid, so that rest periods of theheat transfer fluid in the standby device are obtained and the formationof emulsions can consequently be reversed. Furthermore, a density of theheat transfer fluid is monitored by a sensor 20. Should it beestablished in this way that there is too much water in the standbydevice 19, the control 13 can position the standby device 19 furtherupward into the upper layer of heat transfer fluid 17 and fill itcompletely with new heat transfer fluid. The fact that the layer of heattransfer fluid 17 is at rest most of the time results in that theformation of emulsions has been reversed here and the heat transferfluid has its full protective properties.

Furthermore, this problem can also be solved by the standby device 19being balanced in such a way that, when it is completely filled withheat transfer fluid, it is suspended and, when it contains too muchwater, it sinks. Then, when the standby device is in a specificposition, the valve 15 is opened by the downwardly drawn line and heattransfer fluid is continuously pumped out of the layer of heat transferfluid 17 into the heat transfer circuit, so that the water is forced outdownward from the standby device.

To optimize the heat exchange, the storage reservoir fluid, water, couldalso be used for the heat exchange. For example, using oil as the heattransfer fluid at high temperatures and using water as the heat transferfluid at lower temperatures. This would on the one hand save operatingenergy, since at a low temperature level considerable heat transferfluid has to be circulated until a corresponding amount of energy isyielded, and water has a higher storage density and less fluid has to becirculated in comparison with oil. At high temperature levels, where thedisadvantage of the oil is not as serious because of the higher amountof energy, the advantage of more safe operation with oil as the heattransfer medium, because of the absence of gas bubbles, can be used.Furthermore, higher temperatures can be yielded and stored for examplein a solid-material storage reservoir, where there is no risk ofboiling.

To use the storage reservoir fluid as the heat transfer fluid, oil asthe heat transfer fluid can for example be let out from the standbydevice 19 at the top with the aid of a valve. By further circulation,the standby device 19 and the heat exchange circuit fill with storagereservoir fluid. The standby device 21 continues to contain oil. Theheavier water will, however, run out downward and move in the directionof equal density. To protect the heat exchange system, however, thefluid exchange device must exchange the fluid again. This may take placefor example by the valve 15 being opened by lowering of the standbydevice 19 and the fluid safely being exchanged by the pump or bygravitational exchange of the fluid exchange system.

The fluid standby devices 19, 21 may also be configured in such a waythat they can be positioned in the storage reservoir. For example bybeing balanced, so that when the flow is at a standstill they areimmersed downward at low speed in the storage reservoir and when thereis a flow they are positioned upward by the flow generated by thecirculating pump 9. If the fluid standby devices 19, 21 are to maintaina position, they can be arrested, for example with the aid of anelectromagnetic arresting device. The lower fluid standby device 21 canbe positioned particularly effectively by the flow, since it acts as abaffle plate for flow conduction. In the case of the upper standbydevice 19, the baffle effect is low because of the distributing functionof the standby device 21. This problem can be solved by the lowerstandby device 21 positioning the upper standby device 19 by contact inthe upward direction and the lower standby device 21 subsequently beingmoved downward again into its position by downward drift. This problemcan also be solved by a baffle plate in the line 18 to the standbydevice 19.

This positioning allows any desired layer with any desired layerthickness to be chosen for the heat exchange. As a result, on the onehand the heat exchange fluid can be made available to the heat exchangesystem with a specific temperature and on the other hand the storagereservoir can be discharged and charged in a defined manner. As aresult, unnecessary mixing of the storage reservoir is avoided, wherebythe temperature level of the storage reservoir is preserved and chargedin the best possible way in comparison with conventional chargingdevices. A bypass function is also possible, in that the standby device21 is positioned into the standby device 19, whereby a lower temperaturethan that in the storage reservoir can be made available, or a highertemperature level than would be possible with single circulation of theheat exchange transfer medium can be obtained.

In FIG. 3, an application of the fluid exchange with a high-temperaturestorage reservoir is shown. According to the invention, ahigh-temperature storage reservoir 31 is integrated in the normalstorage reservoir 36 and the heat generation, here a collector 4, can beused for both storage reservoirs. This is particularly advantageous,since on the one hand the losses of the high-temperature storagereservoir 31 are reduced by the lower temperature difference withrespect to the normal storage reservoir 36 in comparison with anexternal high-temperature storage reservoir, and the losses stilloccurring in the high-temperature storage reservoir 31 are used in thenormal storage reservoir 36. Furthermore, shared use of the collector 4has the effect that, when there is full solar radiation, thehigh-temperature storage reservoir can be charged and, when there islimited solar radiation, the normal storage reservoir can be charged,whereby the cost-effectiveness is increased in comparison with separatesystems. Advantageous here is the use of oil as the heat transfer fluidand heat storage reservoir fluid for the high-temperature function,since oils have significantly higher boiling points than water forexample. For the normal storage reservoir there is the possibility ofusing water or oil as the heat transfer medium and water as the storagereservoir fluid, and using the oil as a protective fluid, as describedin FIG. 2. The high-temperature storage reservoir 31 is thermallyinsulated with respect to the normal storage reservoir 36. This may takeplace for example with the aid of a tank wall made of foam glass, thesurfaces being sealed, for example with a layer of glass or layer ofmetal.

The fluid arriving in the storage reservoir is distributed in a fluidstandby device 35 for direct heat exchange. If water comes from the heatexchange system 4, it would rise or fall in the storage reservoir waterof the normal storage reservoir 36, depending on the temperaturedifference. No water can get into the high-temperature storage reservoir31 even when an opening 32 is open, since it is filled with oil and thisis lighter than water. If oil is circulated by the heat exchange system4, it is also circulated through the high-temperature storage reservoir31 when the opening 32 of the latter is open, and gives off the heat orabsorbs it. At high temperatures of the oil, the hot oil would make thestorage reservoir water evaporate and thereby disturb the circulation.This can be avoided by making the opening 32 be situated slightly lowerthan the standby device 35, which fits exactly into the opening 32. As aresult, the standby device 35 can be positioned into the opening 32,whereby on the one hand an opening to the high-temperature storagereservoir 35 remains but the flow only takes place in the oil. Acorrespondingly thick layer of oil downward to the water produces aninsulation during the fluid circulation, so that the water does notevaporate. Furthermore, the positioning of the standby 35 allows theopening 32 to be closed, so that an oil circulation can also take placethrough the normal storage reservoir 36, whereby the optimized heatexchange in the heat exchange system 4 is made possible.

Here, the oil is directed via fluid directing plates 33, 34 into an areaof the normal storage reservoir 36 in such a way that it can becollected by the fluid standby device with collecting function 29 andreturned to the heat exchange system 4. The standby device 29 isconfigured as a channel running around the high-temperature storagereservoir, but otherwise has the same function as the standby device 19in FIG. 2. A valve 26, a layer of oil 27, the lines 28, 22, 23 and thedevices in the heat exchange system 4 also have the same function as inFIG. 2.

However, the layer thickness would not be completely freely selectable,since the standby device 35 can only be positioned to a restrictedextent. This can be achieved, however, by an additional standby devicein the form of the standby device 29, though configured to be somewhatsmaller. Here, however, the directing devices 33, 34 should direct theflow in a concentrated form, so that only a small heat exchange can takeplace, and the heat exchange only takes place by the distribution of theflow in the additional standby device.

Shown in FIG. 4 is an exemplary embodiment of the method according tothe invention in which the heating system is equipped with a fluidstandby and heat exchange conduction. By contrast with FIG. 1, theprotective fluid is in this case constantly kept at least partly in theheat exchange system 4, and is consequently also a heat transfer fluid.As a result, the fluid exchange device is also no longer needed.However, the heat transfer fluid is then for example oil, which does nothave the high heat density of water, so that more oil has to becirculated for heat exchange in comparison with water, which results ina somewhat greater operating energy. This can be used for example forsingle solar collectors or for heating circuits with low circulation.

This is achieved by a fluid standby device 44 being built into thestorage reservoir 36, an emptying pipe 46 and a filling pipe 45overlapping, so that there is always protective fluid in the fluidstandby tank 44 and, as a result of the flow 16 of the heat exchangesystem likewise being immersed in the protective fluid 17, there islikewise always protective fluid in the heat exchange system. This hasthe effect that the frost protection, corrosion protection and boilingprotection are achieved in the heat exchange system 4.

The heat exchange in the storage reservoir 36 takes place by the directheat exchange of fluids, the heat transfer fluid being passed throughthe storage reservoir by meandering flow conduction 39. This extensionof the path covered by the heat transfer fluid makes optimum heatexchange possible. The feeding of the flow and the discharge of the flowto and from the heat-exchanging flow conduction 39 is carried out with aconcentrated flow 43, 37. This is achieved by concentrated emptying 46,38 from the fluid standby 44 and a collecting device at theheat-exchanging fluid directing device 39. This achieves the effect thatthe heat exchange takes place as far as possible only in the area of thedirecting device 39.

With the aid of the fluid collecting device 42, the concentrated flow 43is collected and distributed for example into a thin flow curtain andtransferred to the directing device. The thin flow curtain 40 and thestructured surface of the directing device produce a good heat exchangewith little use of material. The directing plates 42 prevent the flowfrom flowing away from the heat-exchanging flow conduction 39.

The positioning of the heat-exchanging flow conduction 39 in the storagereservoir allows any desired layer with any desired layer thickness tobe chosen for the heat exchange. This allows the heat exchange fluid onthe one hand to be made available to the heat exchange system with aspecific temperature and on the other hand the storage reservoir to bedischarged and charged in a defined manner, with the advantagesdescribed with respect to FIG. 2. The layer thickness of the flowconduction can be chosen with the aid of a lower arresting device and anupper arresting device, in that on the one hand the upper end of theflow conduction 39 and at a different point in time the lower end of theflow conduction 39 are positioned by them. The positioning in a layerthen advantageously takes place likewise in two steps, in that the twoends of the flow conduction 39 are likewise positioned one after theother. The balancing of such a dynamic system, where the upward lift ordownward drift is not exactly defined due to changing fluid contents,can present problems. This is solved by the positionable flow conductionbeing balanced in such a way that, without lighter fluid, it ispositioned downward and, with lighter fluid, it is positioned upward, sothat the flow conduction is positioned downward when the arrestingdevice is released and the circulation is at a standstill and ispositioned upward when there is circulation.

By use of the standby and the exchange of media, media with at least onedifferent property, such as heat storage density, evaporationtemperature, evaporating property, freezing temperature, oxygenabsorption, oxygen rejection, absorption property, emission property,density, viscosity, storage capacity, thermal conductivity or mixingproperties, can be adjusted precisely for the respective operatingfunction, whereby the latter can be operated optimally. This allows theheat transfer medium to be configured for example for optimum storageand/or heat production and also for cost-effective heat exchange, whileat the same time protective functions can be achieved.

The fact that the protective function keeps the fluid and/or corrosionprotection in a liquid state allows regenerative heating systems to beoperated at higher temperatures without pressure systems having to beused for them.

Advantageous for a simple configuration is the method that water 7, 36and/or oil 3, 17, 27, 31, 35, 44, 43, 40, 37, 19, 21, 29, such asparaffin oil, mineral oil, synthetic oil, are predominantly used asfluids. As a result, a high storage density is achieved by the water,and protection against frost, boiling and excessive temperature isachieved by the heat transfer medium of oil. If paraffin oil is used,good corrosion protection is ensured, since paraffin oil is an inertliquid and the components are wetted with it.

Also beneficial is the method that at least one medium is kept onstandby and/or exchanged in at least one media-storing area of a heatingsystem, such as with partitions, vessels with openings with or without avalve in media-containing tanks. This allows not only fluids but alsogases or special fluids for thermal functions or protective functions tobe kept on standby and/or exchanged. In this case, media-storing areas,such as an inert gas tank 1, fluid heat storage reservoir 7, 36, fluidstorage heat exchanger, heating boiler, fluid tank, charging device,provision-on-standby device, fluid exchange device, heating boiler,fluid exchange lines, exchanging area, storage reservoir or fluid gravelstorage reservoir, can be supported in their operating functions. Forexample, the transport of gas within oil for venting or for heatexchange is obtained in this way.

The method that media are kept on standby by floating 3, 17, 27 and/orbeing immersed 19, 21, 29, 31, 35 in fluids 7, 36 allows on the one handsimple configurations of such a heating system and on the other handmore complex functionality to be ensured.

This is advantageously achieved by the standby performing at least oneof the following functions: flow conduction 21, 19, 35, 29, 38, 42, 44,flow shaping 21, 35, 44, 42, 38, charging 21, 35, 44, provision onstandby 19, 29, 38, 62, 68, media collection or media separation. Themethod whereby the exchange of media takes place by stored forms ofenergy, such as fluid level differences 7, 10; 36, 10, pressuredifferences and/or forms of energy that are not generated, such asgravitational force, differences in gravitational force, upward lift ordownward drift, ensures the safe exchange of media. Furthermore, thecirculation, and with it an exchanging operation, can take place in onedirection in a media exchange system with a pump, while the exchangingoperation can be carried out in a protective function with theaforementioned forms of energy.

The method that the exchange of fluids takes place by receiving at leastone fluid in a tank 10 allows heating systems with a higher fluid levelto carry out the exchange of media. The tank 10 can be fitted at anylevel below the fluid level, and consequently any heating system with afluid level is suitable for the exchange. The tank 10 may be an exchangetank of its own or some other tank capable of receiving fluid, such as afluid storage reservoir, storage heat exchanger, inert gas tank, heatingboiler.

It is particularly advantageous that, when exchanging fluids, at leastone further medium 3, 17, 27 is drawn in its place. This allowscirculating systems to be provided with loops of differing height withprotective functions. This allows for example solar collectors to beconnected with the absorbers interconnected in all possible ways. Whereemptying of solar circulating systems takes place in the prior art,these can only be provided as circulating systems with a gradient in twodirections, i.e. without height loops with frost protection. In the caseof solar circulating systems with one or two directions of the gradientin the area of protection, it is sufficient for the heat transfer fluidto be displaced by a protective fluid. This can be achieved by aprotective fluid that is lighter or heavier than the heat transfer fluidbeing let in from the bottom or from the top. As a result, the exchangetank 10 can be omitted from heating systems for which cost is a dominantfactor.

The fact that the exchange of media takes place with an exchange flowwhich counteracts the upward lift of the lighter medium in the densermedium achieves the effect that the entire medium in a circulatingsystem is exchanged. The medium to be exchanged cannot collect at pointsof reversal, since it is entrained by the correspondingly great flow.

The beneficial method that the exchange of the fluids is completed whena protective fluid exceeds a defined point in the heat exchange system 4ensures that the circulating system is safely filled with a protectivefluid. This can be achieved by detecting the protective fluid by adensity sensor and/or by collecting a defined amount of fluid 10 and/orby determining a defined missing amount of fluid in an area 3, 17, 27.

The exchange of gas achieves the effect of flushing throughheat-transferring gas media, whereby low-cost thermal functions can beaccomplished with a heating system.

With the aid of the method that at least one line of a heat exchangesystem 4 can be immersed 2 or introduced in or connected 14, 26 to astored fluid, the exchange of the fluid is prepared, and the fluid to beexchanged can be stored in fluid-storing heating components.

With the aid of the method that the exchange is made possible by use ofat least one compliant element, such as a membrane or gas area, theexchange can take place with little energy and in pressurized orunpressurized heating systems or heating systems with a fluid level.This element yields each time an exchange occurs, so that the exchangetank 10 can be filled and emptied. The compliant element may in thiscase be located in the storage reservoir or in the standby device.

If paraffin oils are used as a protective fluid in areas at risk offrost, the problem arises that cold is predominantly introduced intoinsulated areas and the cold is retained by the insulation, andconsequently viscous oil sticks in this area, so that the exchange, i.e.starting after frost, would be possible only with great pumpingpressure. In the case of relatively small insulated areas of cold, thisproblem can be solved cost-effectively by use of positive-displacementpumps, which can supply a corresponding pressure. Otherwise, the methodthat heat exchange systems or parts thereof can raise and/or store atemperature is suitable for solving this problem. Simple possible waysof realizing this are solar heating from a collector or by transparentheat insulation or from a heat storage reservoir. The heat transfer mayin this case take place by air and intermediate spaces in insulatedareas of cold, where the air is allowed into the intermediate spacesand/or circulated. This method may also be used for the purpose ofkeeping the temperature above the freezing point or critical viscositytemperature, if this is not too energy-intensive, for example when thereis a light frost and/or great insulation.

With the aid of the method that actions for safe exchange, such asestablishing a connection from the area to be protected 4 to theprotective fluid 17, 27, positioning standby devices or valve actuationsat exchange systems, are obtained by use of the safe forms of energyexchange with protective functions can be safely ensured without energyhaving to be supplied in the case of protection. For example, exchangecan safely take place by use of valves 15, 26 or positionable linesmoved by upward-lifting or downward-drifting bodies 19, 29 and/or movedby the difference in fluid level of the storage reservoir or insulatingheat exchanger and fluid receiving tank 10 and/or moved by thedifference in pressure of the storage reservoir or storage heatexchanger and fluid receiving tank.

Further safety is obtained by the presence and/or absence of the fluidsin the heating system and/or in areas of a heating system beingmonitored to achieve safe exchange. This can take place with an upwardlift sensor 8, downward drift sensor, conductivity sensor, fluid levelsensor, fluid presence sensor, density sensor or amount-of-fluidmeasuring sensor. As a result it can be ensured that, in the case ofprotection, the protective fluid is introduced throughout an area to beprotected.

Significant safety is achieved by the method that, for safe fluidexchange, the exchange is safely ensured by redundant measures, such asredundant elements, redundant operations or autonomous additionaldevices. Redundant elements may include thermostats, temperaturesensors, valve-controlled emptying lines and/or exchange lines,evaluation units of sensors, fluid presence sensors or fluid absencesensors with and without a valve-controlled emptying line and/orexchange lines or controls. Redundant operations may be repeatoperations, such as repetitions of an exchange, repeated activation ofredundant exchange devices, or operations for overcoming malfunctions,such as logging of malfunctions, or flushing operations. Autonomousadditional devices may be realized for example by a thermostat and anevaluation unit which establishes a safe state.

Increased safety is also achieved by the activating voltage foractuators relevant to safety, such as pumps 9, exchange devices orvalves 11, 12, taking place by concatenation via at least one redundantsystem, such as a control, thermostat or evaluation unit, and theactivating voltage being enabled by all the systems, and the transfer tothe safe state of the activating voltage taking place even if only onesystem withdraws enablement. This allows safe states likewise to beestablished by control devices in the event of malfunctions.

High efficiency is provided by the method that the direct heat exchangetakes place by at least one flow 21-19, 35-33-29, 40 and/or by at leastone storing area 21, 19, 35, 29 of the media.

The increase in the heat exchange performance is initiated according tothe invention by the heat exchange being carried out and/or intensifiedby at least one flow conduction 21, 35, 44, 39 and/or flow shaping 21,35, 42. This allows an extension of the path covered by the heatexchange medium and/or an increase in its heat exchanging surface. Amixing of the heat exchange media is also possible as a result.

The flow conduction advantageously takes the form that at least one flowof the media is conducted freely in a medium 35-29, 37, 43 and/or partlyfreely 39, such as at directing plates, directing channels, directingsheets, and/or embedded in other media, such as in flexible connections60, 70. This achieves on the one hand an exactly defined temperaturespace and on the other hand large heat exchanging surface areas in asmall space.

With the aid of conducting free or partly free flows throughfluid-storing areas, on the one hand constant flows and division of theflows are achieved and on the other hand the storing area can also actas a storage heat exchanger.

The fact that the flow conduction 39 and/or flow introduction is changedin the inclination with respect to the horizontal, such as by being setor subjected to closed-loop or open-loop control, allows vortexing to beproduced, or flow conductions can be changed with regard to the spacethey are to flow through, thereby realizing for example layerthicknesses flowed through according to choice.

The fact that the flow conduction 39 takes place in a meandering and/orspiral form through the media-storing area means that contiguous flowconductions can be realized, allowing a large heat-exchanging surfacearea to be produced with little space. Heat exchanging influences arebrought about by the flow conduction 39 and/or flow introduction 21, 35,42 effecting flow-influencing, such as accelerating, retarding,vortexing, path-extending or surface-enlarging, flows. This can besupported by structures on directing plates and/or rotatable flowshaping devices and/or laminar flows. The flow can also be influenced bychannels, convexities, inclinations influencing rates of flow, roundedportions, settling zones or quantity-controlled settling zones, so thatthey can be conducted and/or distributed in a laminar manner.

Advantageous charging with heat or provision of heat on standby is madepossible by the method that at least one of the following elements:standby 21, 35, 44, collection 19, 29, 32, 38, flow shaping 21, 35, 44,42, 38, forms of flow 37, 43, 40, flow conduction 21, 35, 44, diversion33, 34, 41, flow deflection, flexible conduction, sensors 20, 30 ormedia separation, to flow directing devices is used for at least onethermal function. This allows the charging to take place in temperaturespaces and heat to be provided at the appropriate temperature with anexactly defined sensor level without mixing of a medium.

Beneficial for good heat exchange or for minimal heat exchange,depending on the location of the flow, is the method that at least oneflow is shaped, such as a centered flow 43, 37 and/or distributed flow21, 35, 40. This allows a flow with a large surface or with a minimizedsurface and vortexed or laminar flow to be produced. As a result, flowsto or from a temperature space can be realized freely with the smallestheat exchange and flows in a temperature space with a great heatexchange performance. For the variability of the heat exchange it isappropriate for the method to take place with the flow conduction and/orflow variably with regard to the form and/or in a number of forms. Forexample, flows with a centered and small surface 43, 37 and/or in a flatform 40 and/or in a radiated form with a large surface and/or in theform of bubbles or drops and/or with different cross sections, flowcurtains and/or flow rivulets and/or flow jets and/or flows in the formof drops and/or bubbles and/or pulses and/or dispersed forms, such as ina spray form, rain form, sprinkling form, and/or wetted forms. Changingthe forms or the number of forms also allows adaptation of the heatexchanging performance, for example for provision at the appropriatetemperature.

The method that orifices and/or flow shaping devices of media lines arerotatable and/or pivotable, predominantly driven by the fluid flow,allows media mixing or different devices with which flow is realized tobe aimed at, according to choice, such as standby devices, flowconduction devices, provision-on-standby devices or charging devices.

To solve emulsion problems, it is advantageous that an emulsificationreversal is promoted in the system and/or an emulsion formation isavoided. For example, this can take place by the collecting areas 3, 17,19, 21, 27, 29, 35, 42, 38 and/or constricting outlets of the fluids 38,such as funnels, funnels with outlets with a small inclination withrespect to the horizontal, returns into the collecting area from thelower or upper area of the outlet conduction, flow-stabilized areas,large interfaces between the fluids, rest periods for fluids beforerenewed circulation, returns from boundary areas separating devices,such as density-dependent floating partition walls or laminar flowconduction.

The method by which the charging and/or provision of media on standbytakes place with positionable flow deflections and/or with fixed flowdeflections, which are subjected to flow by the flow conduction,provides a simple and cost-effective way of realizing such functions.This involves for example a flow with a small surface being directedupward onto a flow deflection, and this flow being deflected into a flowwhich is horizontal and with an enlarged surface, whereby the heatexchange begins from the position of the deflection and ends for examplein a standby device.

It is helpful during charging and provision on standby that the flow isminimized during charging and/or provision on standby, such as by flowmeasurement in the layer or by spatial expansion of the flow. Themeasurement and/or spatial expansion may take place in this case at theflow deflection. The flow can also be minimized by defined rates of flowfor selected layers by the control of the flow through the circulatingpump. Undesired mixing is also avoided in this way.

The fact that at least one positionable standby device or collectingdevice is used for charging and/or providing media areas on standbyallows them to act as storage heat exchangers in temperature spaces, apartly direct heat exchange being carried out between the media at theopened points of the standby device.

In the method, at least one external and/or internal medium, such asexhaust gas, air, water, waste water or oil, is introduced into and/ordischarged from the heating system. This allows heat to be exchangedwith direct heat exchange with external elements which are not directlyassigned to the heating or which use different heat transfer media thanthe heating system. Examples of this may be use of heat from waste gasor use of waste heat from machines or components. The selection ofexternal media and the discharge of internal media takes place howeveron the basis of the conditions of the heating system with regard todeposits, corrosion protection and media separation.

Advantageous introduction and/or discharge of media takes place byintroduced and/or discharged media being introduced into and/ordischarged from a flow and/or a storing area. Air is introduced forexample in flows, so that it is transported into fluid pressure areasand can rise again with a heat-exchanging effect.

For introduction and discharge with low operating costs, theintroduction and/or discharge of internal and/or external media willtake place in an area of the heating system and/or of the externalsystem where similar pressure conditions prevail. In the case of air,this is with a flow in unpressurized heating systems, whereapproximately atmospheric pressure prevails. Fluids from different fluidpressure columns are exchanged at points with the same fluid pressurecolumns and differences in density are used for the exchange in thefluid area.

The aforementioned method is also used for performing the exchangingand/or circulating of media within the heating system with differentpressure conditions and/or fluid levels in areas where similar pressureconditions prevail, the media possibly being passed on. With the aid ofthis method, media can be exchanged with low operating costs in storagereservoirs with different fluid levels, since pressure differences donot have to be overcome by pumps and the heat exchange can be performedwith provision on standby and/or charging devices.

Taking this a stage further is also the method that high-temperaturefunctions of the thermal functions take place by use of at least onemedium, so that temperatures which lie above those of the boilingtemperature of water are yielded and stored for example by a heattransfer media formed from paraffin oil, without a pressure increasehaving to take place. This allows higher temperatures to be exchangedand stored in heating systems without pressurization, wherebycost-effectiveness increases.

It is also advantageous that the operating devices of the heating systemin FIG. 3, such as collectors, heating boilers, heat exchange systems,control devices or protective devices, can be used fornormal-temperature functions and for high-temperature functions. Thisalso facilitates the storage and use of higher temperatures.

Losses from high-temperature storage can be used by the method, by thehigh-temperature storage reservoir (FIG. 3) or storage heat exchangerbeing integrated in a normal-temperature storage reservoir or storageheat exchanger, predominantly in a thermally insulated manner. Thelosses are then absorbed by the normal-temperature storage.

It is expedient that the heat transfer medium for the exchange and/orfor the high-temperature storage is a heat transfer oil and/or solidsubstance, such as scrap metals, concrete or a mixture of crushed stoneand sand. For example, it is appropriate for a high-temperature storageto be configured such that the heat transfer oil can take the averageyield of a day, and this yield is passed on to a solid-substance storagereservoir, the storage size being determined by the solid-substancestorage reservoir. The high-temperature functions may be used forregenerative use of heat, such as increasing the storage capacity,and/or for cooking and/or baking and/or for processes, such as melting,welding, evaporating or sterilizing, and/or for chilling and/or coolingfunctions, such as of machines, motors, collectors, fuel cells, exhaustgases or processes and/or for rapid heating functions, such as for roomswhere the heat has been lowered, rooms used for a short time or roomsopened at times or in part, and/or for thermal irradiation.

Heating systems with devices such as a fluid exchange device, a fluidstandby device, a device for direct heat exchange between media, adevice for introducing and/or discharging media or separating device,such as a reverse-emulsification device or emulsion avoiding device, canperform the thermal and protective functions at lower cost in comparisonwith the prior art. It is possible here to do withoutprovision-on-standby devices, heat exchangers and operating devices forheat exchanger systems, and heat sources can simply be used for storingthe heat.

A heating system in which a fluid exchange device contains a fluidreceiving tank 10 and the pump 9 of the heat exchange system can carryout the fluid exchange also when the fluid level or storage reservoirarea of the heating system lies above the areas to be protected. Thisalso allows gravitational force to be used for the fluid exchange.

With the aid of the separation of the fluid receiving tank 10 and theheat exchange system and/or of the storage reservoir by at least onevalve 11, 12, 25 in each case, it is possible for the exchange operationand the fluid retaining operation to be controlled.

It is beneficial if the fluid receiving tank 10 is a tank of its ownand/or a fluid-storing area of the heating system, such as a fluid heatstorage reservoir or heating boiler, but also a fluid storage heatexchanger, a tank connected to a heat exchanger or an inert gas tank.This allows the fluid receiving tank to be used for heat storage orfunction tanks to be used in two forms.

It is cost-effective and materially productive that one or more heatexchange systems are served by one fluid exchange device.

This also applies because the media standby device is implemented bypartitions, such as plates or vessels. Low-cost examples of partitionsmay also be sheets, dishes, depressions, channels, bags or containers.

The fact that in the case of standby devices one is overlapping over atleast one other and/or over at least one flow, so that overflows of themedia and/or inflows are safely collected and/or the standby devices canbe positioned in one another, results in that the standby device isconstantly operational and is suitable for producing bypasses.Particularly advantageous for the standby function is that a standbydevice 21, 35, 29, 44, 42, 38 has at least one of the following devices:an overflow 46, valve, collecting area 19, 29, opening, storing area 21,35, flexible flow line, integrated flow conduction, connection to theheat exchange system 2, 22, 67, sensor 20, 30, conduction 64, coupling,fluid exchange area, gas removal, flow shaping 21, 35, 44, 42, 38 orflow shaping storing area. Therefore, standby devices can be configuredto have a good heat-exchanging effect or heat-exchange intensifyingeffect. Furthermore, the formation of emulsion can be avoided orpromoted or reversed. As a result, the freely selectable charging oftemperature spaces and provision of media at appropriate temperaturescan also be realized with the standby device.

1. A method for operating a heating system using media, the heatingsystem being selected from the group consisting of a solar heatingsystem, a substance-operated heating system, a heat-absorbing heatingsystem, a heat-storing heating system, and a combination heating systemformed of a combination of the aforementioned heating systems, whichcomprises the steps of: exchanging, in at least part of the heatingsystem, at least part of one additional fluid for at least one thermalfunction for a fluid located in the part of the heating system; andkeeping a remainder of the additional fluid on standby.
 2. The methodaccording to claim 1, wherein protective functions keep the fluid and/orcorrosion protection in a liquid state.
 3. The method according to claim1, which further comprises selecting water to be the fluid and oil to bethe additional fluid.
 4. The method according to claim 1, wherein adirect heat exchange can take place between the media, including fluids,gas and fluid or emulsion and fluid, and the direct heat exchange takesplace in heat exchange circulation without fluid exchange in a standbystate.
 5. The method according to claim 1, which further compriseskeeping at least one of the media on standby and/or exchanged in atleast one media-storing area of the heating system.
 6. The methodaccording to claim 1, which further comprises keeping the additionalfluid on standby by floating and/or being immersed in the fluid.
 7. Themethod according to claim 5, wherein the standby performs at least oneof the following functions: flow conduction; flow shaping; charging;provision on standby; media collection; and media separation.
 8. Themethod according to claim 1, wherein an exchange of the media takesplace by stored forms of energy and/or pressure differences and/or formsof energy that are not generated.
 9. The method according to claim 1,which further comprises performing the exchanging step by receiving atleast one of the fluids in a tank.
 10. The method according to claim 9,which further comprises performing the exchanging step by the additionalfluid being drawn in the place of the fluid and/or displacing the fluid.11. The method according to claim 1, which further comprises performingthe exchange step with an exchange flow which counteracts an upward liftof a lighter medium in a denser medium.
 12. The method according toclaim 1, which further comprises: completing the exchanging of thefluids step when the additional fluid exceeds a defined point in a heatexchange system; and detecting the additional fluid by a density sensorand/or by a method of collecting a defined amount of the additionalfluid.
 13. The method according to claim 1, wherein by the exchangingstep of at least one media, gas can also be exchanged.
 14. The methodaccording to claim 1, wherein at least one line of a heat exchangesystem can be immersed or introduced in or connected to a stored fluid.15. The method according to claim 1, which further comprises performingthe exchanging step by use of at least one compliant element selectedfrom the group consisting of a membrane and a gas area.
 16. The methodaccording to claim 1, further comprising providing heat exchange systemsor parts thereof for raising and/or storing a temperature, so thatcritical temperatures are avoided.
 17. The method according to claim 8,wherein actions for safe exchange, such as establishing a connectionfrom an area to be protected to the additional fluid functioning also asa protective fluid, include positioning standby devices or valveactuations at heat exchange systems and using the stored forms of energyand/or the pressure differences and/or the forms of energy that are notgenerated.
 18. The method according to claim 1, which further comprisesmonitoring for a presence and/or an absence of the fluids in a heatingsystem for achieving a safe exchange.
 19. The method according to claim1, wherein for safe fluid exchange, the exchanging step is safelyperformed using redundant measures, including redundant elements,redundant operations and autonomous additional devices.
 20. The methodaccording to claim 1, which further comprises providing an activatingvoltage for actuators relevant to safety, including pumps, exchangedevices and valves, to take place by use of concatenation via at leastone redundant system, including a control or thermostat, and theactivating voltage is enabled by all systems, and a transfer to a safestate of the activating voltage takes place even if only one systemwithdraws enablement.
 21. The method according to claim 1, which furthercomprises performing a heat exchange by use of at least one flow and/orby use of at least one storing area of the media.
 22. The methodaccording to claim 1, which further comprises carrying out and/orintensifying heat exchange by at least one flow conduction and/or flowshaping.
 23. The method according to claim 1, which further comprisesconducting at least one flow of the media freely in a medium and/orpartly freely, such as at directing plates, directing channels,directing sheets, and/or embedded in other media, such as in flexibleconnections.
 24. The method according to claim 1, which furthercomprises conducting free or partly free flows through fluid-storingareas.
 25. The method according to claim 23, which further compriseschanging a flow conduction and/or a flow introduction in an inclinationwith respect to a horizontal, such as by being set or subjected toclosed-loop or open-loop control.
 26. The method according to claim 25,which further comprises forming the flow conduction to take place in ameandering and/or spiral form through a media-storing area.
 27. Themethod according to claim 25, wherein the flow conduction and/or flowintroduction effects flow-influencing.
 28. The method according to claim1, which further comprises providing at least one element selected fromthe group consisting of standby devices, collection devices, flowshaping devices, forms of flow devices, flow conduction devices,diversion devices, flow deflection devices, flexible conduction devices,sensors and media separation devices, all being flow directing devicesproviding at least one thermal function.
 29. The method according toclaim 28, which further comprises shaping at least one flow to be acentered flow and/or a distributed flow.
 30. The method according toclaim 1, wherein a flow conduction and/or flow takes place variably withregard to form and/or in a number of forms, such as with flow curtainsof variable extent and/or variable number or dispersed forms.
 31. Themethod according to claim 1, wherein orifices and/or flow shapingdevices of media lines are rotatable and/or pivotable, predominantlydriven by a fluid flow.
 32. The method according to claim 1, whichfurther comprises promoting an emulsification reversal in a heatingsystem and/or an emulsion formation is avoided, such as by use ofcollecting areas, rest periods for fluids before renewed circulation orseparating devices.
 33. The method according to claim 25, whereincharging and/or provision of media on standby takes place withpositionable flow deflections and/or with fixed flow deflections, whichare subjected to flow by the flow conduction.
 34. The method accordingto claim 33, which further comprises minimizing a flow during thecharging and/or provision on standby, by use of flow measurement in atemperature space or by spatial expansion of the flow.
 35. The methodaccording to claim 1, which further comprises using at least onepositionable standby device or collecting device for providing the mediaon standby and/or for charging media-storing areas at appropriatetemperatures.
 36. The method according to claim 1, which furthercomprises introducing at least one external and/or internal mediumselected from the group consisting of exhaust gases, air, water and oil,into and/or discharged from the heating system.
 37. The method accordingto claim 36, wherein introduced and/or discharged media are introducedinto and/or discharged from a flow and/or a storing area.
 38. The methodaccording to claim 1, which further comprises introducing and/ordischarging of internal and/or external media in an area of the heatingsystem and/or of an external system where similar pressure conditionsprevail.
 39. The method according to claim 1, which further comprisesexchanging and/or circulating of the media within the heating systemwith different pressure conditions and/or fluid levels takes place inareas where similar pressure conditions prevail, the media possiblybeing passed on.
 40. The method according to claim 1, which furthercomprises using at least one medium for performing high-temperaturethermal functions.
 41. The method according to claim 1, whereinoperating devices of the heating system, selected from the groupconsisting of collectors, heat exchange systems and protective devices,can be used for normal-temperature functions and for high-temperaturefunctions.
 42. The method according to claim 1, which further comprisesintegrating a high-temperature storage reservoir or a storage heatexchanger in a normal-temperature storage reservoir or a storage heatexchanger, predominantly in a thermally insulated manner.
 43. The methodaccording to claim 1, which further comprises using a heat transfer oiland/or solid substance, selected from the group consisting of scrapmetals, concrete and a mixture of crushed stone and sand, as a heattransfer medium for an exchange and/or for high-temperature storage. 44.The method according to claim 3, which further comprises selecting theoil from the group consisting of paraffin oil and synthetic oil.
 45. Themethod according to claim 1, which further comprises using theadditional fluid for performing the thermal function selected from thegroup consisting of heat exchange, heat transfer, and heat storage. 46.The method according to claim 8, wherein: the stored forms of energyinclude fluid level differences; and the forms of energy that are notgenerated include gravitational forces, upward lifts and downwarddrifts.
 47. The method according to claim 5, which further comprisesselecting the media-storing area from the group consisting of partitionsand vessels with openings with or without a vale in media-containingtanks.
 48. The method according to claim 27, which further comprisesselecting the flow-influencing from the group consisting of vortexingflows, path-extending flows and or surface-enlarging flows.
 49. Aheating system, comprising: at least one apparatus selected from thegroup consisting of: a fluid exchange device for drawing one fluid afteranother; a fluid standby device for keeping a fluid on standby againstan upward lift or a downward drift; and a device for direct heatexchange between media, said device selected from the group consistingof media standby devices and devices for introducing and/or dischargingexternal media.
 50. The heating system according to claim 49, whereinsaid fluid exchange device includes a fluid receiving tank and a pump.51. The heating system according to claim 50, further comprising: astorage reservoir; a heat exchange system; and valvesseparating/connecting said fluid receiving tank, said heat exchangesystem, and/or said storage reservoir.
 52. The heating system accordingto claim 51, wherein: said fluid receiving tank is a separate tankand/or a fluid-storing area of the heating system, selected from thegroup consisting of a fluid heat storage reservoir and a heating boiler.53. The heating system according to claim 49, further comprising atleast one heat exchanging system and said fluid exchange device servingsaid at least one heat exchange system.
 54. The heating system accordingto claim 49, wherein said media standby device includes partitions. 55.The heating system according to claims 49, wherein in a case of saidstandby devices, one of said standby devices overlapping over at leastanother one of said standby devices and/or over at least one flow, sothat overflows of the media and/or inflows are safely collected and/orsaid standby devices can be positioned in one another.
 56. The heatingsystem according to claim 49, wherein said media standby device has atleast one of the following devices: an overflow pipe, a valve, acollecting area, an opening formed therein, a storing area, a flexibleflow line, an integrated flow conduction, a connection to a heatexchange system, a sensor, a conduction, a coupling, a fluid exchangearea, a gas removal device, a flow shaping device or a flow shapingstoring area.
 57. The heating system according to claim 49, furthercomprises devices for controlled ventilation and/or for regenerative useof heat.
 58. The heating system according to claim 54, wherein saidpartitions are selected from the group consisting of plates and vessels.59. A method of operating a system, which comprises the steps of:providing the heating system according to claim 49; and using theheating system for controlled ventilation and/or for regenerative use ofheat.